1. Field of Invention
The present invention relates to a heat dissipation device and an impeller thereof. More particularly, the present invention relates to an axial-flow fan and a blade structure thereof.
2. Description of Related Art
There are several types of heat dissipation device on the market, including fans and blowers, and fans are commonly used in personal computers. Fans are suitable for a system with low impedance. That is, the static pressure of fans is lower.
FIGS. 1A and 1B illustrate a conventional fan having a frame 10 and an impeller 11. The impeller 11 includes a hub 111 and a plurality of blades 112 arranged around the hub. When airflow is generated by the impeller motivated by a driving means (such as motor) and passes through the hub 111 and blades 112 of the fan, air turbulence 12 (as illustrated in FIG. 1B) may occur when the airflow encounters the top surface of the hub so that the volume and the blast pressure of airflow discharged from the fan will be greatly reduced. Thus, it is desired to develop a fan which can improve a fan which can improve the above-described problems.